UNIVERSITY   OF   CALIFORNIA 

COLLEGE    OF    AGRICULTURE 
AGRICULTURAL   EXPERIMENT  STATION 

CIRCULAR  No.  226 
December,  1920 

PROTECTION  OF  VINEYARDS  FROM  PHYLLOXERA 

By  FBEDEKIC  T.  BIOLETTI 


The  phylloxera  is  a  minute  insect  which  attacks  the  roots  of  the 
vine,  and  which  has  destroyed  about  100,000  acres  of  vineyard  in 
California  alone.  It  has  found  its  way  into  parts  of  the  coast  counties 
from  Mendocino  to  San  Luis  Obispo  and  of  the  interior  counties  from 
Yuba  and  Glenn  to  Tulare.  It  spreads  slowly  but  surely  in  the  in- 
terior and  somewhat  more  rapidly  in  districts  nearer  the  coast. 

Means  of  Dispersal. — The  phylloxera's  most  rapid  method  of 
spreading  to  new  vineyards  is  by  means  of  the  winged  form  which 
appears  occasionally  in  the  cooler  districts,  but  apparently  never  in 
the  warmer  interior.  It  is  usually  introduced  into  new  districts  by 
means  of  rooted  vines  brought  in  from  infested  areas.  It  may  also 
be  brought  in  with  cuttings,  boxes,  implements,  and  even  boots  that 
have  been  used  in  infested  vineyards. 

It  spreads  very  slowly  from  vine  to  vine  below  ground  on  the  roots 
and  more  rapidly,  sometimes,  by  crawling  short  distances  over  the 
surface  of  the  ground. 

Quarantine. — The  spread  of  phylloxera  can  be  much  delayed  by 
disinfecting  all  material — vines,  cuttings,  boxes,  implements — coming 
from  a  suspected  locality  to  an  uninfested  vineyard. 

Cuttings  and  rooted  vines  can  be  disinfected  by  treatment  with 
water  at  122°  F.  for  five  minutes  as  follows: 
Equipment : 

1.  An  accurate  dairy  or  other  thermometer  indicating  to  212°  F. 

2.  A  cauldron  of  a  capacity  of  twenty  to  thirty  gallons,  or  a  small 
boiler. 

3.  Two  fifty-gallon  wooden  barrels,  open  at  one  end,  or  any  other 
containers  of  that  capacity. 

4.  A  fork  for  the  quick  and  easy  removal  of  the  treated  stock  from 
the  disinfecting  barrels. 

Method  of  procedure : 

Cuttings  in  bundles  can  be  disinfected  without  any  preliminary 
treatment.  Rooted  vines  should  first  be  pruned,  then  washed  to  remove 
soil,  and  tied  up  in  bundles  of  about  100. 

The  disinfection  is  carried  out  as  follows:  Place  one  bundle  of 
rooted  vines  in  barrel  A,  filled  two-thirds  full  with  water  at  104°  F., 
and  leave  it  for  two  minutes.  Then  remove  the  bundle  from  barrel  A 
and  place  it  in  barrel  B,  containing  water  at  exactly  122°  F.,  and  leave 


Z  UNIVERSITY  OF    CALIFORNIA EXPERIMENT   STATION 

for  five  minutes.  Stirring  the  bundles  in  the  heated  water  will  make 
the  sterilization  more  effective.  No  part  of  a  bundle  should  be  allowed 
to  be  above  the  surface  of  the  water. 

Great  care  should  be  taken  in  keeping  the  water  of  barrel  B  at 
122°  F.  This  can  be  easily  done  by  adding  a  little  boiling  water  from 
the  cauldron  between  treatments  of  bundles. 

The  temperature  of  the  water  of  barrel  A  should  be  kept  at  about 
104°  F.  A  drop  of  a  few  degrees  in  barrel  A,  however,  is  of  slight 
consequence,  as  this  barrel  is  used  merely  to  give  the  bundles  of  vines 
a  preliminary  warming  in  order  that  they  will  not  cool  the  water  in 
barrel  B  below  122°  F. 

A  watch  or  other  timepiece  placed  in  a  suitable  position  is  necessary 
for  accurately  timing  the  immersion. 

The  disinfected  cuttings  or  rooted  vines  must  be  packed  in 
phylloxera-free  packing  material  and  can  then  be  planted  safely  or 
shipped  into  any  district. 

Probability  of  Infestation. — The  probabilities  of  infestation  vary 
from  zero  to  certainty.  In  excessively  sandy  soils,  such  as  the  blow 
sands  of  parts  of  the  San  Joaquin  Valley  and  of  southern  California, 
the  phylloxera  can  not  live  and  the  vines  are  safe.  In  soil  from  which 
vines  killed  by  phylloxera  have  just  been  removed  any  new  vines 
planted  are  certain  to  be  infested  from  the  start  and  are  likely  to  die 
before  they  produce  a  single  paying  crop.  Between  these  extremes 
all  degrees  of  probability  occur. 

In  heavily  infested  parts  of  the  coast  region,  such  as  Sonoma,  Napa, 
and  Santa  Clara  counties,  it  is  unsafe  to  plant  non-resistant  vines, 
except  perhaps  in  a  few  isolated  mountain  valleys  well  protected  from 
the  winged  insect  by  a  screen  of  hills  and  woods. 

In  other  parts  of  this  region  single  vineyards  are  fairly  safe  if  the 
indicated  precautions  against  the  introduction  of  the  insect  are  taken. 
Where  many  vineyards  are  planted  near  together,  however,  some  grow- 
ers are  very  apt  to  neglect  these  precautions  and  phylloxera  introduced 
into  one  vineyard  will  rapidy  spread  to  neighboring  vineyards. 

In  the  San  Joaquin  Valley  it  is  seldom  advisable  to  use  resistant 
roots,  except  in  the  districts  where  the  phylloxera  is  known  to  occur. 
Even  in  these  districts  it  is  probably  best  not  to  plant  them  in  new 
land  if  a  mile  or  more  from  an  infested  vineyard.  If  the  soil  is  more 
or  less  sandy,  deep,  rich,  and  well  supplied  with  water  for  irrigation, 
the  danger  of  rapid  infestation  and  destruction  of  the  vines  is  less. 
In  heavy  loams  and  clay  soils  the  danger  is  greater. 

In  counties  and  sections  which  appear  to  be  free  from  phylloxera 
no  resistant  vines  should  be  planted,  even  for  experiment  purposes, 
unless  carefully  disinfected  under  the  direction  of  a  horticultural  com- 
missioner. Phylloxera  may  be  carried  and  will  breed  on  resistant  roots. 
This  makes  these  roots  dangerous  in  an  uninfcsted  district,  as  they 
may  spread  the  pest  without  showing  any  signs  of  damage  themselves. 

Resistant  Vines. — The  roots  of  certain  American  vines  are  practi- 
cally uninjured  by  attacks  of  the  phylloxera  and  can  be  used  as  graft- 
ing stock  to  protect  susceptible  vines.  All  the  varieties  of  vines  that 
we  grow  for  grapes  are  susceptible.    The  grapes  of  resistant  vines  are 


CIRCULAR  226         PROTECTION   OF   VINEYARDS   FROM   PHYLLOXERA  3 

of  no  value,  but  varieties  grafted  on  them  produce  the  same  grapes  as 
when  ungrafted. 

When  to  Use  Resistant  Vines. — The  use  of  resistant  roots  is  insur- 
ance, and  like  most  insurance  has  a  cost.  They  should  be  used  there- 
fore only  when  their  cost  is  considerably  less  than  the  probable  loss 
from  the  use  of  non-resistant  roots.  This  may  be  estimated  if  we  know 
the  probable  duration  of  the  two  kinds  of  vineyards.  The  duration  of 
a  non-resistant  vineyard  depends  on  a  number  of  conditions  con- 
sidered in  the  discussion  of  the  probability  of  infestation.  Let  us 
suppose  that  a  vineyard,  resistant  or  non-resistant,  would  remain 
profitable  for  twenty  years  if  there  were  no  invasion  of  phylloxera. 
Let  us  assume  for  one  set  of  conditions  that  the  non-resistant  vineyard 
would  be  destroyed  by  phylloxera  in  ten  years,  and,  for  another  set,  in 
twenty  years.    Estimates  might  then  be  made  as  follows : 

A.  Non-Eesistant  Vineyard — Probable  Duration,  10  Years 
Cost  of  establishing,  per  acre  $200 

Total  profit  (6  crops)  600 

Loss  of  vineyard  at  10  years  200 

Total  net  profit  - 400 

Annual  net  profit  40 

B.  Non-Eesistant  Vineyard — Probable  Duration,  20  Years 

Cost  of  establishing,  per  acre  $200 

Total  profit  (16  crops)  1600 

Loss  of  vineyard  at  20  years  200 

Total  net  profit 1400 

Annual  net  profit  70 

C.  Eesistant  Vineyard — Probable  Duration,   20  Years 
Cost  of  establishing,  per  acre  $300 

Total  profit  (16  crops)  1440 

Loss  of  vineyard  at  20  years  300 

Total  net  profit 1140 

Annual  net  profit  67 

A  consideration  of  these  estimates  indicates  that  if  a  vineyard  is 
liable  to  infestation  and  destruction  in  a  short  period,  say  ten- years, 
the  extra  cost  of  planting  and  handling  resistant  vines  would  be  justi- 
fied. On  the  other  hand,  if  the  vineyard  were  reasonably  safe  from 
infestation  for  a  long  period,  say  twenty  years,  the  extra  cost  of  re- 
sistant vines  would  be  wasted. 

Skill  and  Experience  Needed. — The  estimates  of  the  relative  profits 
of  resistant  and  non-resistant  vineyards  given  above  are  based  on 
an  increased  first  cost  of  the  resistant  vineyards  of  $100  per  acre  and 
an  annual  increased  cost  of  handling  of  $10.  It  was  further  assumed 
that  the  crops  of  each  would  be  the  same.  These  assumptions  are  true 
only  for  particular  cases. 

If  the  grower  lacks  skill  and  experience  in  the  use  of  resistant 
vines  his  cost  may  be  greater  and  his  crops  will  certainly  be  less.  On 
the  other  hand,  a  skillful  grower  who  knows  how  to  choose,  plant,  and 
handle  a  resistant  vineyard  may  reduce  the  cost  considerably  and  in 


4  UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION 

many  cases  increase  the  amount  and  quality  of  the  crop.  No  grower 
should  attempt  to  grow  a  vineyard  of  resistant  vines,  however  much 
experience  he  has  had  with  ordinary  vineyards,  without  thoroughly 
studying  the  subject. 

He  should  consult  his  farm  advisor,  read  the  publications  on  the 
subject  issued  by  the  College  of  Agriculture,  and  visit  nurseries  and 
vineyards  where  resistant  vines  are  handled.  He  should  know  what 
varieties  of  resistant  stock  are  most  likely  to  give  profitable  results  in 
his  particular  soil  and  climate  and  with  the  variety  of  grape  he  desires 
to  grow.  He  should  know  how  to  recognize  a  good  resistant  grafted 
vine,  how  to  plant  it,  and  how  to  care  for  it  in  the  vineyard,  and  he 
should,  if  possible,  obtain  some  practice  in  all  branches  of  the  work.    ■ 

With  this  preparation,  a  good  farmer  can  safely  plant  a  resistant 
vineyard  and  in  many  cases  the  extra  cost  will  be  returned  by  im- 
proved crops,  even  though  the  phylloxera  never  gets  into  his  district. 
Without  this  preparation  he  is  practically  sure  to  make  a  partial  or  a 
complete  failure. 

Best  Resistant  Stocks. — Hundreds  of  different  resistant  stocks  have 
been  tested  and  used  to  some  extent.  Only  a  few  dozen  have  been  used 
on  a  large  scale.  Only  two,  Rupestris  St.  George  and  Lenoir,  have 
been  used  much  in  California.  Most  of  the  stocks  which  have  given 
satisfaction  in  Europe  have  been  tested  at  Davis,  California,  for  over 
ten  years  and  the  results  make  it  possible  to  recommend  several  stocks 
as  better  than  the  two  most  commonly  used  here.  In  fact,  our  most 
widely  grown  stock,  the  Rupestris  St.  George,  has  given  the  poorest 
average  results  of  the  eighteen  stocks  tested  as  regards  crop  and  vigor. 
The  Lenoir  has  a  good  record  at  Davis,  but  is  not  sufficiently  resistant 
and  has  failed  in  many  vineyards. 

The  stocks  which  can  be  most  safely  recommended  are : 

1.  Chasselas  X  Berlandieri  41-B,  usually  called  "41-B"  for  short. 
This  stock  has  given  the  best  results  with  more  scion  varieties  than 
any  other.  These  varieties  include  Muscat,  Black  Corinth,  Sultana, 
Tokay,  and  Cornichon.  Its  grafts  bear  well  and  are  vigorous  and  long 
lived.    It  suffers  less  from  drought  than  most  stocks. 

2.  Riparia  X  Rupestris  3309,  usually  referred  to  as  "3309."  This 
stock  follows  close  to  41-B  and  is  somewhat  easier  to  graft.  It  has 
given  the  best  results  with  Sultanina  (Thompson),  Emperor,  and 
Palomino,  among  others. 

3.  Riparia  X  Rupestris  3306,  referred  to  as  "  3306. ' '  This  has  been 
the  best  stock  for  Malaga  and  White  Corinth. 

These  stocks  have  been  well  tested  only  at  Davis  and  at  Kearney, 
but  there  seems  every  reason  to  suppose  that  they  will  be  found  ex- 
cellent for  most  or  all  other  parts  of  California  where  grape  growing 
is  feasible.  They  have,  with  all  varieties,  in  all  cases  given  better 
results  than  St.  George  or  Lenoir,  with  one  exception,  the  raisin  Muscat. 
This  variety  is  hard  to  suit  in  the  matter  of  a  stock  and  many  cases  of 
failure  are  reported  from  the  numerous  countries  where  it  is  grown. 
It  usually  bears  well  when  grafted,  but  the  grafted  vines  on  most  stocks 
are  short  lived.  Its  record  at  Davis  on  41-B  is  excellent.  It  lacks 
vigor  and  bears  poor  crops  on  3309  at  Kearney,  where  St.  George  has 
given  better  results,  though  its  durability  on  this  stock  is  in  doubt. 


